Age-related antibody response to Orthopoxviruses and implications for public health measures: Insights from a South Korean study.

BACKGROUND: After the eradication of smallpox, there have been no specific public health measures for any Orthopoxviruses (OPXVs). Therefore, it is necessary to countermeasure OPXV infections after Mpox (formerly monkeypox) occurrences, such as the latest global outbreak in 2022-2023. This study aimed to provide crucial insights for the development of effective public health policy making against mpox in populations residing in regions where the virus is not prevalent. METHODS: This study used enzyme-linked immunosorbent assays (ELISA) to examine smallpox and mpox antibodies in Koreans with three different age groups. We analyzed 56 sera obtained from a tertiary care hospital in South Korea between September 2022 and April 2023. Plasma levels of antibodies against the viral proteins of smallpox (variola cytokine response-modifying protein B) and MPXV (A29) were measured using enzyme-linked immunosorbent assays. RESULTS: Plasma samples from participants in their early 40 s and older exhibited higher reactivity to viral antigens than those from younger participants. Furthermore, there was a strong positive correlation in antibody positivity for the two different viruses across the sera. CONCLUSIONS: The presence of low antibody levels in participants ˂40 years may hinder their ability to defend against OPXV. Therefore, it is imperative to implement effective public health measures to mitigate the transmission of OPXV within the community. These findings serve as fundamental information for devising strategies to combat mpox efficiently, particularly in regions where the virus is not prevalent.

Strategy to develop broadly effective multivalent COVID-19 vaccines against emerging variants based on Ad5/35 platform.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron strain has evolved into highly divergent variants with several sub-lineages. These newly emerging variants threaten the efficacy of available COVID-19 vaccines. To mitigate the occurrence of breakthrough infections and re-infections, and more importantly, to reduce the disease burden, it is essential to develop a strategy for producing updated multivalent vaccines that can provide broad neutralization against both currently circulating and emerging variants. We developed bivalent vaccine AdCLD-CoV19-1 BA.5/BA.2.75 and trivalent vaccines AdCLD-CoV19-1 XBB/BN.1/BQ.1.1 and AdCLD-CoV19-1 XBB.1.5/BN.1/BQ.1.1 using an Ad5/35 platform-based non-replicating recombinant adenoviral vector. We compared immune responses elicited by the monovalent and multivalent vaccines in mice and macaques. We found that the BA.5/BA.2.75 bivalent and the XBB/BN.1/BQ.1.1 and XBB.1.5/BN.1/BQ.1.1 trivalent vaccines exhibited improved cross-neutralization ability compared to their respective monovalent vaccines. These data suggest that the developed multivalent vaccines enhance immunity against circulating Omicron subvariants and effectively elicit neutralizing antibodies across a broad spectrum of SARS-CoV-2 variants.

Intranasal administration enhances size-dependent pulmonary phagocytic uptake of poly(lactic-co-glycolic acid) nanoparticles.

BACKGROUND: Nanoparticles exhibit distinct behaviours within the body, depending on their physicochemical properties and administration routes. However, in vivo behaviour of poly(lactic-co-glycolic acid) (PLGA) nanoparticles, especially when administered nasally, remains unexplored; furthermore, there is a lack of comparative analysis of uptake efficiency among different administration routes. Therefore, here, we aimed to comprehensively investigate the real-time in vivo behaviour of PLGA nanoparticles across various administration routes. PLGA-NH2 nanoparticles of three sizes were synthesised using an oil-in-water single-emulsion method. We assessed their uptake by murine macrophage RAW264.7 cells using fluorescence microscopy. To enable real-time tracking, we conjugated p-SCN-Bn-deferoxamine to PLGA-NH2 nanoparticles and further radiolabelled them with 89Zr-oxalate before administration to mice via different routes. Nanoparticle internalisation by lung immune cells was monitored using fluorescence-activated cell sorting analysis. RESULTS: The nanoparticle sizes were 294 ± 2.1 (small), 522.5 ± 5.58 (intermediate), and 850 ± 18.52 nm (large). Fluorescent labelling did not significantly alter the nanoparticle size and charge. The level of uptake of small and large nanoparticles by RAW264.7 cells was similar, with phagocytosis inhibition primarily reducing the internalisation of large particles. Positron emission tomography revealed that intranasal delivery resulted in the highest and most targeted pulmonary uptake, whereas intravenous administration led to accumulation mainly in the liver and spleen. Nasal delivery of large nanoparticles resulted in enhanced uptake by myeloid immune cells relative to lymphoid cells, whereas dendritic cell uptake initially peaked but declined over time. CONCLUSIONS: Our study provides valuable insights into advancing nanomedicine and drug delivery, with the potential for expanding the clinical applications of nanoparticles.

Histopathological pulmonary lesions in rhesus (Macaca mulatta) and cynomolgus (Macaca fascicularis) macaques experimentally infected with wild-type severe acute respiratory syndrome coronavirus 2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes a viral pneumonia characterized by acute interstitial pneumonia and diffuse alveolar damage in humans. Non-human primates (NHPs) are widely used as preclinical animal models for vaccine development against SARS-CoV-2. However, the pathological changes in NHPs have been described only in selected facets and inconsistent nomenclature is used, making it difficult to interpret and compare the outcomes between studies. Here, we present a standardized methodology for histopathological evaluation of experimental infection outcomes in rhesus (Macaca mulatta) and cynomolgus (Macaca fascicularis) macaques. Evaluation criteria for vascular and epithelial changes in the early (3 days post infection [dpi]) and late (21 dpi) phases of the infection were developed, and a four-grade classification encompassing all the histopathological lung lesions was established. The grades of histopathological lung lesions were higher at 3 dpi compared with 21 dpi in both species of macaques, and there were no statistically significant differences in the grades between the two species at 3 dpi and 21 dpi. This study contextualized the pathological SARS-CoV-2 presentation and standardized the terminology and grading scale for lesion severity to facilitate histopathological examination in the macaque model. By referring to the standardized histopathological criteria and grades proposed here, comparable results with high reproducibility can be obtained in future studies of pathogenicity.

Synchronous Diagnosis of Respiratory Viruses Variants via Receptonics Based on Modeling Receptor-Ligand Dynamics.

The transmission and pathogenesis of highly contagious fatal respiratory viruses are increasing, and the need for an on-site diagnostic platform has arisen as an issue worldwide. Furthermore, as the spread of respiratory viruses continues, different variants have become the dominant circulating strains. To prevent virus transmission, the development of highly sensitive and accurate on-site diagnostic assays is urgently needed. Herein, a facile diagnostic device is presented for multi-detection based on the results of detailed receptor-ligand dynamics simulations for the screening of various viral strains. The novel bioreceptor-treated electronics (receptonics) device consists of a multichannel graphene transistor and cell-entry receptors conjugated to N-heterocyclic carbene (NHC). An ultrasensitive multi-detection performance is achieved without the need for sample pretreatment, which will enable rapid diagnosis and prevent the spread of pathogens. This platform can be applied for the diagnosis of variants of concern in clinical respiratory virus samples and primate models. This multi-screening platform can be used to enhance surveillance and discriminate emerging virus variants before they become a severe threat to public health.

Demonstration of transverse ligament on 3D SPACE MRI in whiplash-associated disorder and nontraumatic conditions.

PURPOSE: This study aims to delineate the three-dimensional (3D) SPACE MRI findings of the transverse ligament (TL) in whiplash-associated disorder (WAD) patients, and to compare them with those from a nontraumatic group. METHODS: A retrospective analysis was performed on cervical spine MRI scans obtained from 46 patients with WAD and 62 nontraumatic individuals. Clinical features, including the WAD grade and stage, were recorded. The TL's morphological grade and the symmetricity of the lateral atlantodental interval was assessed using axial 3D T2-SPACE images. The morphological grading was evaluated using a four-point scale: 0 = homogeneously low signal intensity with normal thickness, 1 = high signal intensity with normal thickness, 2 = reduced thickness, 3 = full-thickness rupture or indistinguishable from surrounding structures. Additionally, the number of cervical levels exhibiting degeneration was documented. RESULTS: When comparing the WAD and nontraumatic groups, a significant difference was observed in the proportion of high-grade TL changes (grade 2 or 3) and the number of degenerated cervical levels. Logistic regression analysis revealed that high-grade TL changes and a lower number of degenerative levels independently predicted the presence of WAD. Within the WAD group, the subset of patients with high-grade TL changes demonstrated a significantly higher mean age than the low-grade group (grade 0 or 1). CONCLUSION: High-grade morphological changes in the TL can be detected in patients with WAD through the use of 3D SPACE sequences. Clinical relevance statement 3D SPACE MRI could serve as an instrumental tool in the assessment of TL among patients with WAD. Integrating MRI findings with patient history and symptomology could facilitate the identification of potential ligament damage, and may help treatment and follow-up planning.

mRNA-HPV vaccine encoding E6 and E7 improves therapeutic potential for HPV-mediated cancers via subcutaneous immunization.

The E6 and E7 proteins of specific subtypes of human papillomavirus (HPV), including HPV 16 and 18, are highly associated with cervical cancer as they modulate cell cycle regulation. The aim of this study was to investigate the potential antitumor effects of a messenger RNA-HPV therapeutic vaccine (mHTV) containing nononcogenic E6 and E7 proteins. To achieve this, C57BL/6j mice were injected with the vaccine via both intramuscular and subcutaneous routes, and the resulting effects were evaluated. mHTV immunization markedly induced robust T cell-mediated immune responses and significantly suppressed tumor growth in both subcutaneous and orthotopic tumor-implanted mouse model, with a significant infiltration of immune cells into tumor tissues. Tumor retransplantation at day 62 postprimary vaccination completely halted progression in all mHTV-treated mice. Furthermore, tumor expansion was significantly reduced upon TC-1 transplantation 160 days after the last immunization. Immunization of rhesus monkeys with mHTV elicited promising immune responses. The immunogenicity of mHTV in nonhuman primates provides strong evidence for clinical application against HPV-related cancers in humans. All data suggest that mHTV can be used as both a therapeutic and prophylactic vaccine.

Spatial transcriptome atlas reveals pulmonary microstructure-specific COVID-19 gene signatures in cynomolgus macaques.

Characterizing the host response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at the molecular level is necessary to understand viral pathogenesis and identify clinically relevant biomarkers. However, in humans, the pulmonary host response during disease onset remains poorly understood. Herein, we utilized a spatial transcriptome atlas to identify pulmonary microstructure-specific COVID-19 gene signatures during the acute phase of lung infection in cynomolgus macaques. The innate immune response to virus-induced cell death was primarily active in the alveolar regions involving activated macrophage infiltration. Inflamed vascular regions exhibited prominent upregulation of interferon and complement pathway genes that mediate antiviral activity and tissue damage response. Furthermore, known biomarker genes were significantly expressed in specific microstructures, and some of them were universally expressed across all microstructures. These findings underscore the importance of identifying key drivers of disease progression and clinically applicable biomarkers by focusing on pulmonary microstructures appearing during SARS-CoV-2 infection.

Comparative spatial transcriptomic profiling of severe acute respiratory syndrome coronavirus 2 Delta and Omicron variants infections in the lungs of cynomolgus macaques.

Recently emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variants are generally less pathogenic than previous strains. However, elucidating the molecular basis for pulmonary immune response alterations is challenging owing to the virus's heterogeneous distribution within complex tissue structure. Here, we revealed the spatial transcriptomic profiles of pulmonary microstructures at the SARS-CoV-2 infection site in the nine cynomolgus macaques upon inoculation with the Delta and Omicron variants. Delta- and Omicron-infected lungs had upregulation of genes involved in inflammation, cytokine response, complement, cell damage, proliferation, and differentiation pathways. Depending on the tissue microstructures (alveoli, bronchioles, and blood vessels), there were differences in the types of significantly upregulated genes in each pathway. Notably, a limited number of genes involved in cytokine and cell damage response were differentially expressed between bronchioles of the Delta- and Omicron-infection groups. These results indicated that despite a significant antigenic shift in SARS-CoV-2, the host immune response mechanisms induced by the variants were relatively consistent, with limited transcriptional alterations observed only in large airways. This study may aid in understanding the pathogenesis of SARS-CoV-2 and developing a clinical strategy for addressing immune dysregulation by identifying potential transcriptional biomarkers within pulmonary microstructures during infection with emerging variants.

Heterologous vaccination utilizing viral vector and protein platforms confers complete protection against SFTSV.

Severe fever with thrombocytopenia syndrome virus was first discovered in 2009 as the causative agent of severe fever with thrombocytopenia syndrome. Despite its potential threat to public health, no prophylactic vaccine is yet available. This study developed a heterologous prime-boost strategy comprising priming with recombinant replication-deficient human adenovirus type 5 (rAd5) expressing the surface glycoprotein, Gn, and boosting with Gn protein. This vaccination regimen induced balanced Th1/Th2 immune responses and resulted in potent humoral and T cell-mediated responses in mice. It elicited high neutralizing antibody titers in both mice and non-human primates. Transcriptome analysis revealed that rAd5 and Gn proteins induced adaptive and innate immune pathways, respectively. This study provides immunological and mechanistic insight into this heterologous regimen and paves the way for future strategies against emerging infectious diseases.

Suramin binds and inhibits infection of SARS-CoV-2 through both spike protein-heparan sulfate and ACE2 receptor interactions.

SARS-CoV-2 receptor binding domains (RBDs) interact with both the ACE2 receptor and heparan sulfate on the surface of host cells to enhance SARS-CoV-2 infection. We show that suramin, a polysulfated synthetic drug, binds to the ACE2 receptor and heparan sulfate binding sites on the RBDs of wild-type, Delta, and Omicron variants. Specifically, heparan sulfate and suramin had enhanced preferential binding for Omicron RBD, and suramin is most potent against the live SARS-CoV-2 Omicron variant (B.1.1.529) when compared to wild type and Delta (B.1.617.2) variants in vitro. These results suggest that inhibition of live virus infection occurs through dual SARS-CoV-2 targets of S-protein binding and previously reported RNA-dependent RNA polymerase inhibition and offers the possibility for this and other polysulfated molecules to be used as potential therapeutic and prophylactic options against COVID-19.

Pyruvate dehydrogenase kinase inhibitor dichloroacetate augments autophagy mediated constraining the replication of Mycobacteroides massiliense in macrophages.

Increasing evidence indicates a strong interaction between cellular metabolism and innate macrophage immunity. Here, we show that the intracellular replication of Mycobacteroides massiliense in macrophages depends on host pyruvate dehydrogenase kinase (PDK) activity. Infection with M. massiliense induced a metabolic switch in macrophages by increasing glycolysis and decreasing oxidative phosphorylation. Treatment with dichloroacetate (DCA), a PDK inhibitor, converts this switch in M. massiliense-infected macrophages and restricts intracellular bacterial replication. Mechanistically, DCA resulted in AMPKα1 activation via increased AMP/ATP ratio, consequently inducing autophagy to constrain bacterial proliferation in the phagolysosome. This study suggests that the pharmacological inhibition of PDK could be a strategy for host-directed therapy to control virulent M. massiliense infections.

Ethanol extract of Chrysanthemum zawadskii inhibits the NLRP3 inflammasome by suppressing ASC oligomerization in macrophages.

Chrysanthemum zawadskii (C. zawadskii) is used in traditional East Asian medicine for the treatment of various diseases, including inflammatory disease. However, it has remained unclear whether extracts of C. zawadskii inhibit inflammasome activation in macrophages. The present study assessed the inhibitory effect of an ethanol extract of C. zawadskii (CZE) on the activation of the inflammasome in macrophages and the underlying mechanism. Bone marrow-derived macrophages were obtained from wild-type C57BL/6 mice. The release of IL-1ß and lactate dehydrogenase in response to nucleotide-binding oligomerization domain-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome activators, such as ATP, nigericin and monosodium urate (MSU) crystals, was significantly decreased by CZE in lipopolysaccharide (LPS)-primed BMDMs. Western blotting revealed that CZE inhibited ATP-induced caspase-1 cleavage and IL-1ß maturation. To investigate whether CZE inhibits the priming step of the NLRP3 inflammasome, we confirmed the role of CZE at the gene level using RT-qPCR. CZE also downregulated the gene expression of NLRP3 and pro-IL-1ß as well as NF-κB activation in BMDMs in response to LPS. Apoptosis-associated speck-like protein containing a caspase-recruitment domain (CARD) oligomerization and speck formation by NLRP3 inflammasome activators were suppressed by CZE. By contrast, CZE did not affect NLR family CARD domain-containing protein 4 or absent in melanoma 2 inflammasome activation in response to Salmonella typhimurium and poly(dA:dT) in LPS-primed BMDMs, respectively. The results revealed that three key components of CZE, namely linarin, 3,5-dicaffeoylquinic acid and chlorogenic acid, decreased IL-1ß secretion in response to ATP, nigericin and MSU. These findings suggest that CZE effectively inhibited activation of the NLRP3 inflammasome.

Incidental Diagnosis of Ovarian Torsion Due to a Krukenberg Tumor Originating from Gastric Cancer: A Case Report.

BACKGROUND: Benign lesions cause ovarian torsion more commonly than malignant ovarian tumors. Further, Krukenberg tumors have rarely been reported to cause ovarian torsion. CASE PRESENTATION: Herein, we present the case of a patient with an incidentally discovered ovarian mass, which was finally diagnosed as a Krukenberg tumor accompanying ovarian torsion with primary stomach cancer. We further review the clinical, imaging, and histological features of Krukenberg tumors. CONCLUSION: Radiologists should be aware of Krukenberg tumors that may present with ovarian torsion.

Monocytes as suitable carriers for dissemination of dengue viral infection.

Dengue viruses (DENVs) exploit monocytes and macrophages for tropism and replication, therefore, establishing a long-term reservoir. However, their roles in dengue pathogenesis remains unclear. Here, using the human monocytic cell line THP-1, human primary monocytes, and non-human primate models, we show that DENV-infected monocytes represent suitable carriers for circulatory viral dissemination. Monocyte-derived macrophages expressing M2 surface markers at the gene level efficiently replicated, while the productivity of monocyte replication was low. However, attachment of DENVs to the cellular surface of monocytes was similar to that of macrophages. Furthermore, after differentiation with type-2 cytokines, DENV-attached monocytes could replicate DENVs. Productive DENV infection was confirmed by intravenous injection of DENVs into nonhuman primate model, in which, DENV attachment to monocytes was positively correlated with viremia. These results provide insight into the role of circulating monocytes in DENV infection, suggesting that monocytes directly assist in DENV dissemination and replication during viremia and could be applied to design antiviral intervention.

Liposomal Dexamethasone Reduces A/H1N1 Influenza-Associated Morbidity in Mice.

Re-emerging viral threats have continued to challenge the medical and public health systems. It has become clear that a significant number of severe viral infection cases are due to an overreaction of the immune system, which leads to hyperinflammation. In this study, we aimed to demonstrate the therapeutic efficacy of the dexamethasone nanomedicine in controlling the symptoms of influenza virus infection. We found that the A/Wisconsin/WSLH34939/2009 (H1N1) infection induced severe pneumonia in mice with a death rate of 80%, accompanied by significant epithelial cell damage, infiltration of immune cells, and accumulation of pro-inflammatory cytokines in the airway space. Moreover, the intranasal delivery of liposomal dexamethasone during disease progression reduced the death rate by 20%. It also significantly reduced the protein level of tumor necrosis factor-alpha (TNFα), interleukin-1ß (IL-1ß), IL-6, and the C-X-C motif chemokine ligand 2 (CXCL2) as well as the number of infiltrated immune cells in the bronchoalveolar lavage fluids as compared to the control and free dexamethasone. The liposomal dexamethasone was mainly distributed into the monocyte/macrophages as a major cell population for inducing the cytokine storm in the lungs. Taken together, the intranasal delivery of liposomal dexamethasone may serve as a novel promising therapeutic strategy for the treatment of influenza A-induced pneumonia.

Vaccination inducing durable and robust antigen-specific Th1/Th17 immune responses contributes to prophylactic protection against Mycobacterium avium infection but is ineffective as an adjunct to antibiotic treatment in chronic disease.

Mycobacterium avium complex (MAC) causing pulmonary disease in humanshas emerged worldwide. Thus, effective strategies simultaneously aiming to prevent MAC infection and accelerate therapeutic efficacy are required. To this end, subunit vaccine-induced protection against a well-defined virulent Mycobacterium avium (Mav) isolate was assessed as a preventative and therapeutic modality in murine models. Mav-derived culture filtrate antigen (CFA) was used as a vaccine antigen with glucopyranosyl lipid A stable emulsion (GLA-SE) or GLA-SE plus cyclic-di-GMP (GLA-SE/CDG), and we compared the immunogenicities, protective efficacies and immune correlates. Interestingly, CFA+GLA-SE/CDG immunization induced greater CFA-specific Th1/Th17 responses in both the lung and spleen than among the tested groups. Consequently, protective efficacy was optimally achieved with CFA+GLA-SE/CDG by significantly reducing bacterial loads along with long-lasting maintenance of antigen-specific Th1/Th17 cytokine-producing multifunctional T cell responses and relevant cytokine productions. Thus, we employed this subunit vaccine as an adjunct to antibiotic treatment. However, this vaccine was ineffective in further reducing bacterial loads. Collectively, our study demonstrates that strong Mav CFA-specific Th1/Th17 responses are critical for preventative protection against Mav infection but may be ineffective or even detrimental in an established and progressive chronic disease, indicating that different approaches to combating Mav infection are necessary according to vaccination purposes.

SARS-CoV-2 mutations acquired during serial passage in human cell lines are consistent with several of those found in recent natural SARS-CoV-2 variants.

Since the outbreak of coronavirus disease (COVID-19) in 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has evolved into diverse variants. Here, an early isolate of SARS-CoV-2 was serially passaged in multiple cell lines of human origin in triplicate, and selected mutations were compared to those found in natural SARS-CoV-2 variants. In the spike protein, Q493R and Q498R substitutions from passaged viruses were consistent with those in the B.1.1.529 (Omicron) variant. Y144del and H655Y substitutions from passaged viruses were also reported in B.1.1.7 (Alpha), P.1 (Gamma), and B.1.1.529 (Omicron) variants. Several single nucleotide polymorphisms (SNPs) found in first-passaged viruses have also been identified as selected mutation sites in serially passaged viruses. Considering the consistent mutations found between serially passaged SARS-CoV-2 and natural variants, there may be host-specific selective mutation patterns of viral evolution in humans. Additional studies on the selective mutations in SARS-CoV-2 experiencing diverse host environments will help elucidate the direction of SARS-CoV-2 evolution. Importance: SARS-CoV-2 isolate (SARS-CoV-2/human/KOR/KCDC03-NCCP43326/2020) was serially passaged in A549, CaCO2, and HRT-18 cells in triplicate. After 12 times of serial passages in each cell lines, several consistent selected mutations were found on spike protein between the serially passaged SARS-CoV-2 in human cell lines and recent natural variants of SARS-CoV-2 like omicron. On the non-spike protein genes, selected mutations were more frequent in viruses passaged in Caco-2 and HRT-18 cells (Colon epithelial-like) than in those passaged in A549 cells (Lung epithelial-like). In addition, several SNPs identified after one round of passaging were consistently identified as the selected mutation sites in serially passaged viruses. Thus, mutation patterns of SARS-CoV-2 in certain host environments may provide researchers information to understand and predict future SARS-CoV-2 variants.

Host-directed anti-mycobacterial activity of colchicine, an anti-gout drug, via strengthened host innate resistance reinforced by the IL-1ß/PGE2 axis.

BACKGROUND AND PURPOSE: To diversify and expand possible tuberculosis (TB) drug candidates and maximize limited global resources, we investigated the effect of colchicine, an FDA-approved anti-gout drug, against Mycobacterium tuberculosis (Mtb) infection because of its immune-modulating effects. EXPERIMENTAL APPROACH: We evaluated the intracellular anti-Mtb activity of different concentrations of colchicine in murine bone marrow-derived macrophages (BMDMs). To elucidate the underlying mechanism, RNA sequencing, biological and chemical inhibition assays, and Western blot, quantitative real-time PCR, enzyme-linked immunosorbent assay (ELISA), and immunohistochemical analyses were employed. Finally, type I interferon-dependent highly TB-susceptible A/J mice were challenged with virulent Mtb H37Rv, and the host-directed therapeutic effect of oral colchicine administration on bacterial burdens and lung inflammation was assessed 30 days post-infection (2.5 mg·kg-1 every 2 days). KEY RESULTS: Colchicine reinforced the anti-Mtb activity of BMDMs without affecting cell viability, indicating that colchicine facilitated macrophage immune activation upon Mtb infection. The results from RNA sequencing, NLRP3 knockout BMDM, IL-1 receptor blockade, and immunohistochemistry analyses revealed that this unexpected intracellular anti-Mtb activity of colchicine was mediated through NLRP3-dependent IL-1ß signalling and Cox-2-regulated PGE2 production in macrophages. Consequently, the TB-susceptible A/J mouse model showed remarkable protection, with decreased bacterial loads in both the lungs and spleens of oral colchicine-treated mice, with significantly elevated Cox-2 expression at infection sites. CONCLUSIONS AND IMPLICATIONS: The repurposing of colchicine against Mtb infection in this study highlights its unique function in macrophages upon Mtb infection and its novel potential use in treating TB as host-directed or adjunctive therapy.